A technique is known to reduce eddy current caused by a fluctuation in an active magnetic field by fracturing a field-pole magnet arranged in a rotor core of a permanent magnet-embedded rotary electric machine into smaller pieces, that is to say, by reducing the surface area of the field-pole magnet. In this way, heating of the field-pole magnet associated with eddy current can be suppressed, and irreversible thermal demagnetization is prevented (see JP 2009-142081A).
According to the technique described in JP 2009-142081A, a cutout is provided to a field-pole magnet in advance as an index of fracture, and then the field-pole magnet is inserted into a container that is filled with resin and has an inner space having the same size and shape as a rotor slot. The field-pole magnet is fractured into magnet pieces inside the container so that the resin penetrates between the magnet pieces at the same time as the fracture.